The present invention relates to a zoom lens, and in particular, to a zoom lens having a high magnifying power and a wide angle which is suitable for an electronic still camera or a video camera employing a solid image pick-up element such as CCD. In particular, it relates to a zoom lens which fits a digital still camera having a large quantity of pixels such as a million pixels or more.
As a zoom lens for a solid image pick-up element such as CCD which has a ratio of variable power of 4 times or more and a wide angle with a half angle of view of 35° or more, there are known a 3-group zoom lens composed of a first lens group with a positive refracting power, a second lens group with a negative refracting power and a third lens group with a positive refracting power disclosed in TOKKAIHEI No. 11-2762, and a 4-group zoom lens composed of a first lens group with a positive refracting power, a second lens group with a negative refracting power and a third lens group with a positive refracting power disclosed in TOKKAIHEI Nos. 7-20381, 7-275361, 6-148521 and 6-148520.
However, though the zoom lens disclosed in TOKKAIHEI No. 11-2762 is a zoom lens with variable magnifications of 5-8 times wherein the number of constituent lenses is made to be small to the utmost, it is difficult to correct various aberrations so that the zoom lens may be used for a high pixel digital still camera having pixels in quantity exceeding a million.
On the other hand, those disclosed in TOKKAIHEI Nos. 7-275361, 6-148521 and 6-148520 represent a zoom lens with a ratio of variable power of 10 or more, and it is still difficult to use this zoom lens for a high image quality digital camera having not less than one million pixels, because distortion and magnification chromatic aberration at an end of a short focal length are not corrected sufficiently.